I run 26psi tops on 100oct.

 

and alky?

 

That's not true in general. I doubt you can achieve MABT (minimum advance for best torque) in an Evo on pump gas. When you run higher octane and advance the timing it's not because you have to, it's because you can!

In the early phase of combustion, flame propagation is dominated by diffusion, so the propagation rate is due to the lighter radical species, H, HO, and HO2, with the fuel characteristics being secondary. In the later phase it's dominated by mass transport due to turbulence.

Where octane comes into play is the pre-flame or cold-flame regimes (before the spark or before the flame-front has reached a region). As you increase the boost or compression you have higher pressures and temperatures so higher concentrations of radical species. Higher octane fuels are more resistant to attack by radicals and slow down the rate of the "cold" reactions. Additives like MMT and TEL quench the radicals.

Dave

 

This seems to imply that more advance is always better, which while true to a point, may amount to risky thinking in certain circles.

I appreciate the insightful blurbs on flame-front mechanics. I wasn't aware that MMT and TEL functioned as radical sinks. Nevertheless, adjusting the timing such that it achieves PCP at the proper range in crankshaft rotation is the ultimate goal. Whether a higher octane fuel means either you can or you have to adjust the advance to reach that point doesn't obscure the fact that it should be expected to be necessary to do so in order to attain said goal (my basic point).

 

Quenching radicals and radical sinks? Getting over my head again , I own a daycare center and get toys out of toilets and sinks I will try to hang with you Ted lol!

 

Yeah, I should be clear I'm assuming that with a nearly 9:1 static CR and lots of boost we're definately on the "retarded" side of MABT with pump gas. I'm pretty sure that's a good assumption. Going beyond that can be a bad thing!

The radicals like OH are pretty high-energy and are happy to tear apart a hydrocarbon. But when they come in contact with "soft" or transition metal compounds they form much more stable species that can't propagate the combustion. Once the flame is going though there's just too much energy around for any octane booster to get in the way of things.

Dave

 

OK, it's a little "out there," but it can be useful to know something about this stuff. Mostly it helps you avoid making expensive mistakes when you're entering new territory. And when you really understand the theoretical side it makes you understand there's no replacement for real experience because real engines are just way more complex than any model. Good thing, otherwise you couldn't get grant money to study them!

Dave

 

No, just pure 100oct.

 

does alky and C16 make any sense at all?

 

It sure does, but it is not needed. I run 28 psi on my car daily with 93 octane and 100% methanol with no problems.

 

I would say start off with 28 psi and check what your EGT's are and check were your AFR's are at. My friend TampaTurbo runs a TT 50 trim at 30 psi daily with 93+ methanol wth great results.

 

Man i wanted to use Methanol too, but they say that it`s too danger
Imagen if 1 drop of methanol will drip on any part under your hood....

May be you know some tricks?
Because i would like to use methanol too


And the 2) If i tuned on WATER, can i add some % of methanol?
Will i see any results?

Thanks

 

for now my boost 33psi on 93octane+WI(water)
without any detonation.But car runs tooooo rich

 

That's Slowwwwwwwwwwwwwwwwwwwwwwwwwwww